Method of forming sheet metal and apparatus therefor



8 Sheets-Sheet l @@@OGC L. A. FRANKS ETAL METHOD OF FORMING SHEET METAL AND APPARATUS THEREFOR Feb. 6, 196s Filed March Feb. 6, 1968 A. FRANKS ETAL 3,367,164

METHOD OF FORMING SHEET METAL AND APPARATUS THEREFR www@ Feb. 6, 1968 A. FRANKS ETAL 3,357,164

METHOD OF FORMING SHEET METAL AND APPARATUS THEREFOR 8 Sheets-Sheet 5 Filed March 5, 1966 Feb- 6, 1968 l.. A. FRANKS ETAL 3,367,164

METHOD OF FORMING SHEET METAL AND APPARATUS THEREFOR 8 Sheets-Sheet Filed March 5, 1966 Feb. 6, v1968 L. A. FRANKS ETAL 3,367,164

METHOD OF FORMING SHEET METAL AND APPARATUS THEREFOR Filed March 3, 1966 8 Sheets-Sheet 5 X X 22 @@@Q Feb 6, 1968 L.. A. FRANKS ETAL 3,367,164

METHOD OF FORMING SHEET METAL AND APPARATUS THEREFOR 8 Sheets-Sheet 6 Filed March 5, 1966 iNvEN'roRs f Www/W mm Vw Af M mi E ME m [N w r MM A Feb. 6, 1968 METHOD OF FOHMING SHEET METAL AND APPARATUS THEREFOR 8 Sheets-Sheet '7 Filed March 5, 1966 United States Patent O 3,367,164.l METHOD F FORMING SHEET METAL AND APPARATUS THEREFOR Lawrence A. Franks and Eugene E. Eldridge, Sturgis,

Mich., assignors to Burr Oak Tool & Gauge Company, Sturgis, Mich., a corporation of Michigan Filed Mar. 3, 1966, Ser. No. 531,545 Claims. (Cl. 72-324) This invention relates in general to a method and apparatus for forming in a sheet of malleable material a plurality of uniformly arranged rows of spaced distortions and, more particularly, to a method and apparatus for forming rows of integral and closely spaced sleeves in the iin of a heat transfer coil.

Finned heat transfer devices, such as heating and cooling coils or radiators, have been used for many years, particularly as part of air conditioning equipment, for example. In order to make this type of equipment available to a wide range of users, it has been necessary to adopt high-speed production procedures, particularly in the manufacture of the finned, heat transfer coils.

Methods have been developed for manufacturing the heat transfer lins accurately and at a high rate of speed, and machines capable of such performance have long been in use. However, two problems7 which have defied solution for a number of years, have tended to place a top limit on the output of existing machinery and, at the same time, have hindered improvement in the quality and performance of the heat transfer surfaces.

Specifically, it has been difficult at best to draw from the fin material sleeves of the desired length through which the fluid-carrying tubes are received, while at the same time providing the desired density of such tubes. The punch and die assemblies in existing machines tend to produce defective sleeves when the centerline distance between adjacent sleeves is as small as desired. That is, the sheet material, such as aluminum, becomes so thin during the drawing process according to existing methods that it often cracks adjacent the sleeves, which not only reduces its ability to transfer heat, but also its ability to resist failure in the presence of stress or vibration. Also, such attempts have often resulted in a thinning out of the metal to the point where its ability to conduct heat is materially reduced.

In order to produce fins at a rate which will be competitive in price, it is necessary to employ a relatively large press and use a relatively large progression-type punch and die assembly, both of which are expensive. It is common knowledge that fins for heat transfer coils can be and usually are manufactured in a great variety of sizes and shapes. That is, heat transfer fins commonly have rows of sleeves which vary in the direction of air flow from two rows to nine rows, for example, and the number of sleeves in any given row may vary from two to 20, for example.

It is also known that existing punch and die assemblies, that are designed for producing heat transfer tins with three rows of sleeves, or whole number multiples thereof in the preferred diamond pattern, cannot be used to produce acceptable two-row heat transfer sleeves, or whole number multiples thereof in the preferred staggered pattern, Thus, if the machine is set to produce fins having an odd number of rows, and a need develops for tins having an even number of rows, it is presently necessary either to use another press having mounted therein a punch and die assembly suited for this purpose, or dismantle the press containing the three-row punch and die assemblies and replace same with the two-row punch and die assemblies.

The relatively small operator cannot afford either the FPice initial cost or the space required to house two presses, one for each type of the punch and die assemblies, and he cannot absorb the loss of time and the cost of maintenance required to change the punch and die assemblies each time a different type of order must be filled. Thus, he is either faced with a large inventory problem or the combination of high cost operation and the inability to supply the right type of fin in an emergency.

It is well known that, in order to extrude a sleeve from a sheet of malleable material, such as aluminum, so that said sleeve can make proper contact with the tubes in a heat transfer device, it is necessary to form the sleeve by a progression of interrelated and sequential operations which are performed by punch and die pairs having a variety of sizes and shapes. Usually, the first punch and die pair in the set along a selected line produces a relatively large dimple in the sheet material. Then, by a series of dimplihg operations, the diameter of the dimple is decreased and its axial extent may be increased. Ultimately, the end wall of the dimple is perforated and the sleeve is thereafter drawn into its finished form. In the past, the distance between adjacent sleeves has often been limited by the diameter of the first dimple since overlapping could not be permitted with the types of punch and die assemblies previously in use.

Accordingly, it has been among the objects and purposes of this invention to provide:

(l) A method and apparatus for producing an improved lin for a heat transfer device in a wide range of sizes and shapes capable of meeting a wide range of needs and capable of performance which is, at least on the average, superior to the performance of fins made from similar material by previously existing machines.

(2) A method and apparatus, as aforesaid, which overcomes a major obstacle to com-petition from the small manufacturer of fins for heat transfer units, and which also permits the improvement of the performance of such fins without increasing their cost.

(3) An apparatus, as aforesaid, which can be quickly and easily adjusted to convert it from the capability of producing fins having odd numbers of rows of sleeves to fins having even numbers of rows, or the reverse.

4) A method and apparatus, as aforesaid, wherein the material in the fin adjacent the location of each sleeve drawn therefrom is worked during the sequence of punching operations to provide a sleeve of maximum strength by comparison to the metal from which it is drawn, and wherein such working is made possible by the arrangement of and sequence of operation of the various pairs of punches and dies in their assemblies.

Other objects and purposes of this invention will become apparent to persons familiar with the forming of distortions in malleable sheet material by means of a punch and die assembly upon reading the following descriptive material and examining the accompanying drawings, in which:

FIGURES 1A and 1B disclose the rear and front portions, respectively, of one side of a punch assembly embodying the invention.

FIGURES 2A and 2B are sectional views of said punch and die assemblies taken along the lines IIA- IIA and IIB-IIB in FIGURES 1A and 1B, respectively.

FIGURES 3A through 3F show fragments of a sheet of material at five stages during the first nine steps of the advancement of said sheet material between the punch and die assemblies, and indicates the effects made upon said sheet material by the punch and die assemblies of the invention.

FIGURES 4A through 4F are sectional views taken along the lines IVA-IVA through IVF-IVF in FIG- URES 3A through 3F, respectively.

FIGURES 5A through 5D are fragments of said sheet 3 material at four stages during the nine steps f advancement following the last step shown in FIGURE 3F.

FIGURES 6A through 6D are sectional views taken along the lines VIAVIA through VID-VID in FIG- URES A through 5D, respectively.

FIGURES 7A and 7B illustrate the four steps of advancement of said sheet material following the last step shown in FIGURE 5D.

FIGURES 8A and 8B are sectional views taken along the lines VIIIA-VIIIA and VIIIB-VIIIB in FIGURES 7A and 7B, respectively.

FIGURE 9 is a broken fragment of the leading end of said sheet material after the punching thereof has been completed.

FIGURE 10 is an enlarged sectional view taken along the line X-X in FIGURE 9.

FIGURE 11 is an enlarged fragment of FIGURE 2A.

FIGURES 12, 13 and 14 are enlarged fragments of FIGURE 2B.

FIGURES 15A and 15B are broken portions of a modified punch assembly.

FIGURES 16A through 16C are fragments of a sheet showing the punch pattern of the assembly in FIGURES 15A and 15B.

FIGURES 17A through 17C are fragments of a sheet between the punch and die assemblies during a two-hole operation.

FIGURES 18 through 22 are fragments of finished tins with various numbers of rows.

For convenience in description, the terms front, rear and words of similar import will have reference to the rightward and leftward ends of FIGURES 1A or 1B and 2A or 2B, respectively. The terms upper, lower and words of similar import will have reference to the punch and die construction as appearing in FIGURES 2A and 2B. The terms innen outer and derivatives thereof will have reference to the geometric center of the punch and die construction to which the invention relates and parts thereof. 'Ihe term crosswise will have reference to a direction substantially perpendicular to the direction of movement of the sheet material through the punch and die assemblies and lengthwise shall refer to a direction parallel with the direction of movement of the sheet material. Also, aligned punch and die pairs crosswise of the sheet movement will be in rows and aligned punch and die pairs lengthwise of the sheet movement will be in linesf IN GENERAL The objects and purposes of the invention, including those set forth above, have been met by providing punch and die assemblies mountable upon the bed and movable platen, respectively, of a press having mechanism capable of effecting advancement of sheet material between the assemblies and performing a shearing operation upon r said sheet material.

The punch assembly, which is mounted upon the bed of the press, includes a plurality of punches arranged in parallel rows substantially perpendicular to the direction of sheet movement. The size and shape of each punch in a given row are preferably identical and said punches are preferably uniformly spaced along each row. Said punches are also arranged in parallel lines lengthwise of sald sheet movement, but the sizes and shapes of the punches vary substantially along each line.

Preferably, the lines of punches are arranged in two patterns which are uniformly repeated crosswise of said sheet movement. However, one line contains one set of punches whereas the other line may contain either one set or two sets. One of the two sets in the other line can be quickly immobilized to permit the use of a three-row punch and die construction to produce two-row ns.

U The die assembly includes a plurality of dies arranged 1n rows, lines and sets for cooperation with said punches.

The method of the invention is carried out by arranging the punches and their cooperating dies in the two or three sets so that the forming operation which produces the integral sleeves by a series of punching operations, is sequenced to provide minimum interference between the set of punch and die pairs which produces one row of sleeves and the punch and die pairs in the set or sets producing sleeves in an adjacent row. By such interrelated sequencing of the punch and die pairs, it is possible for a punch and die pair in one set to perform a preliminary forming operation upon portions of the sheet material which, at a later stage in the operation, is subjected to forming operations by a punch and die pair in another set, without affecting adversely the ultimate extruded sleeve produced by the two punch and die sets.

DETAILED DESCRIPTION The punch and die construction 10, parts of which are disclosed in FIGURES 1A, 1B, 2A and 2B, is comprised of a punch assembly 11 and a die assembly 12 (FIGURE 2A) which are secured, respectively, to the bed 13 and movable platen 14 of a substantially conventional press. Sheet material 16, which is a relatively thin strip or sheet of aluminum in this particular instance, is fed through the space between the punch assembly 11 and die assembly 12 by means of the feed mechanism 17 located at the frontward end (FIGURE 1B) of the punch and die construction 10, and connected to the drive mechanism of the press in a substantially conventional manner.

A shear 18 (FIGURE 2B) is also mounted at the frontward end of the punch and die construction for cutting the sheet material 16 along parallel lines crosswise of the direction of sheet movement. In this particular ernbodiment, said sheet movement is from the leftward or l rearward end of the punch and die construction to its rightward or frontward end, as appearing in FIGURES 1A and 1B, respectively. The shear 18 is also connected to the driving mechanism of the press in a substantially conventional manner.

As shown in FIGURES 2A and 2B, the punch and die construction 10 is provided with a plurality of punch and die pairs, four of which are shown at 21, 22, 23 and 24 in FIGURES 11, 12, 13 and 14, respectively, for illustrative purposes. The punch and die assembly 10 includes a plurality of each of these punch and die pairs, as well as several others, which are arranged in rows crosswise of the sheet movement. The punch and die pairs in any given row are preferably identical, and the pairs in said rows which are part of the same set are spaced from each other along a given line a predetermined distance or a whole number multiple of such distance. In this case, such distance is equal to a whole number multiple of the distance moved by the sheet material during two successive advancements.

In order to carry out the process of the invention, it is necessary that the various types of punch and die pairs be distributed along lines and in spaced positions which are carefully predetermined and which may depend upon the pattern of the sleeves to be extruded from the sheet material and the number of rows per fin in each fin after the shearing operation. For the sake of illustration, and in order to provide a better disclosure of the method and apparatus for carrying it out, the following description will be directed to a punch and die construction wherein threerow tins 19 (FIGURE 9) will be produced with the sleeves 20 arranged in a diamond pattern.

It will be seen that the arrangement of punches and dies shown in FIGURES 1A and 1B can also be used to produce six-row tins (FIGURE 22), merely by changing the cycling of the shearing operation. That is, the sheet material 16 is advanced twice between each movement of the blade 98.

In order to accomplish this versatility, it is necessary to provide three different sets of punch and die pairs along alternating lines, one of which contains the punch and die pairs of one set and the other of which contains the punch and die pairs of two sets. For convenience, the three sets of punch and die pairs are identified by the letters A, B and C (FIGURE 1A), which produce the rear, front and middle rows, respectively, of the sleeves in each three-row fin 19. The four sizes of dimpling punches in set A, for example, are identified by the subscripts 1, 2, 3 and 4. Thus, the largest dimpling punch in each set is identified as A1, B1 and C1, respectively. The punch and die pairs 22, 23 and 24 will be identified by the subscripts 22, 23 and 24 with their appropriate set designations A, B and C.

It will become apparent from the following description that the relative locations of the punch and die pairs in any one set thereof, as well as with respect to the punch and die pairs in the other sets, depend upon the axial length, the diameter, the spacing, the pattern, the material and the rigidity of the sleeves in the completed fin. In this particular embodiment, where three-row tins are being made in a diamond/pattern, it has been found advantageous to advance/"the sheet material between each stroke of the press a distance equal to the centerline distance between corresponding, outside rows of sleeves in two adjacent fins.

It has been found that, if the closest lengthwise distance between adjacent punch and die pairs in any given set is twice the distance of each advancement of the sheet material, or twice the centerline distance between said corresponding rows in two adjacent three-row fins, then said punch and die construction can be used to produce two-row fins. Accordingly, any portion of the sheet material which ultimately becomes a three-row fin after the punching `and shearing operations are completed, must be advanced at least twice between each punching operation performed thereon by the punch and die pairs in any given set. However, it will be seen that operations are sometimes performed simultaneously upon such portion of sheet material by the punch and die pairs in two or more of said sets after a particular advancement.

Perhaps some of the purposes of the invention could be achieved by first performing all of the punching operations required to complete the sleeves in one row of a three-row fin after which all of the punching operations could then be performed by the next set of punch and die pairs to produce the second row of sleeves followed by a similar performance to produce the third row of sleeves. However, this would require an excessively large and expensive punch and die construction, and a corresponding press to handle it. Moreover, it is believed that at least some of the advantages of applicants method stem from gradual increase in the rigidity of the over-all fin structure achieved by work hardening as the sheet material moves through the press and undergoes a sequence of distortions by the punch and die pairs of the various sets. This effect would be minimized where one row is being formed at a time and, in fact, other problems, such as warping, could also be encountered.

For convenience, the row being produced by the punch and die set A will be considered the rear row and will be described first. In this particular embodiment, the punch and die pairs A1, A2, A3 and A4 may be generally similar in construction to the punch and die pair 21 shown in FIGURE 11. That is, a punch guide structure 26 having an upper guide plate 27 is supported upon the bed 13 of the press and provided with a plurality of punch guide openings 28 in which the punches 29 are vertically, slidably disposed. The punch 29 has an enlarged head 32 at its lower end which prevents accidental upward displacement of the punch through the reduced opening 33 in the guide plate 27.

The upper ends of the punches 29 (FIGURE 2A) project upwardly above the guide plate 27 and are slidably, but snugly, received into openings 34 in the stripper plate 35, which is resiliently supported upon the punch guide structure 26 by means such as springs 37. The thickness of the stripper plate 35 and the resiliency of the springs 37 are such that said stripper plate 35 can be moved downwardly by engagement between the punch assembly and the die assembly, in a substantially conventional manner, to permit the upper ends of the punches 29 to move relatively upwardly through the stripper plate 35 and project thereabove the necessary distance to perform a forming operation.

The die assembly 12 includes dies 38 (FIGURE 11) which correspond to and cooperate with the punches 29 in the punch assembly 11. Thus, certain dies correspond to and cooperate with the punches in the punch and die sets A, B and C, as discussed hereinafter. The die 38 (FIGURE 1l) has an opening 39 into which the upper end of the punch 29 is slightly received during the forming operation. Said dies 38 are rigidly secured to a die support plate 42 which is in turn removably anchored upon the upper platen 14 of the press. Similar punch and die structures are provided by the pairs at A1, A2, A3 and A4 (FIGURE 2A), the only difference in this embodiment being that the diameters of the punches and dies are gradually reduced from rear to front.

The stripping plate depressors 44 (FIGURE 2A) are resiliently mounted upon and extend downwardly from the die suport plate 42 at points between the dies 38 for engaging the upper surface of the stripper plate 35 and moving it downwardly so that the upper ends of the punches 29 are adjacent the upper surface of the stripper plate 35 just as the lower faces 46 of the dies 38 press the sheet material 16 'against the upper ends of the punches. Also, said plate depressors 44 serve to hold the sheet material firmly against the upper surface of the striper plate just before and during the engagement of the punches and dies.

When the punch and die pairs A4 have completed their operations upon the dimples 25, the dimples are ready for the final drawing and punching operations which shape the sleeves and remove the outer end of the thimbleshaped dimple. However, it has been :found desirable to perform the piercing or punching operation on all three sleeves at the same time. Thus, the preparation of the sheet material must be brought to this stage of completion with respect to the other two rows of sleeves (produced by the other two sets of punch and die pairs). Accordingly, punch and die pairs A22, which is the next punch and die pair in set A, is spaced a considerable distance frontwardly from the punch and die pair A4 to provide space for the pairs 29 in the B and C sets.

The depth of the dimples 25 produced by the punches 29 is controlled by shims under the punches, such as the shim 47 under the punches 29 and 29A2 (FIGURE 1l), and the shim 48 under the punch 29B1. Moreover, when it becomes desirable, as seen hereinafter, to immobilize one set of punches, whereby the punch and die construction can Ibe used to produce two-row fins, the appropriate shims are merely removed from beneath one set of punches.

The punch and die pair 22 (FIGURE l2) differs from one of the punch and die pairs 21 in that a special insert 51 is placed in the upper surface of the stripper plate 35 around the opening 34. The lower Vface of the die 54, which cooperates with the punch 56, includes an insert 57 having an irregular surface 58 cooperating with the surface 59 on the insert 51 to effect further stretching or distortion of the sheet material around the dimple 25. Then, during the drawing operation performed by the pair 23 (FIGURE 13), this metal is again liattened to increase the amount of metal, hence the strength, in the sheet material closely adjacent the sleeve 20A (FIGURE 7B).

The punch 62 of the punch and die pair 23 (FIGURE 13) has a central opening 63 into which the secondary punch 64 supported in the die 66 is received for punching out the central portion 67 (FIGURE 7B) at the upper 7 end of the dimple 25. At the same time, said dimple 25 is converted into a cylindrical sleeve 20A. The abutting faces 68 and 69 on the punch 62 and die 66, respectively, effect the fiattening operation of the sheet material around said sleeve 20A.

The final forming operation is performed by the punch and die pair 24 (FIGURE 14). That is, the punch 72 has a central opening 73 into which the tapered lower end 74 of a shaping punch 76 is received for providing a are 77 (FIGURE l0) in the upper free edge of the sleeve 20A. In the finished heat transfer unit 19, this are 77 engages the next adjacent fin around the sleeve therein and thereby effects a positive spacing between fins. Accordingly, the operations performed by the punch and die pairs shown in FIGURES l2, 13 and 14 serve not only to determine the ultimate shape and structure of the sleeves 20A, but also to provide the structure necessary for automatic and accurate spacing of the fins when they are finally assembled upon the uid conducting tubes, such as the tube shown in broken lines at 78.

In this particular embodiment, the sheet material 16 (-FIGURES 1A and 1B) will make *10 advancements after the punching operation is performed by the punch and die pair A4 before the punching operation is performed upon the sheet material by the punch and die pair A22, which is the next pair in the punch and die set A. Then, on the third and fifth advancements following the operation `performed -by the punch and die pair A22, the punch and die pairs A22 and A24, respectively, will perform their functions, and this completes the forming operations required by set A to produce a finished sleeve 20 in the sheet material.

The `operations 4performed by the above-des cribed punch and die set A are being simultaneously performed by addional punch and die sets A located in rows crosswise of the punch Iand die construction 10, the number of such sets being governed by the number of sleeves desired or required in the rear row 81 in the final fin 19. For example, if the rear row 81 (FIGURES 9 and 10) is to have l() sleeves, then there must be at least punch and die sets A in the punch and die construction 10. However, a punch and die assembly having or 30 punch and die sets A can be used to provide fins having a lesser number of sleeves per row simply by using the appropriate width of sheet material and properly guiding it in a wellknown manner through rthe punch and die construction so that said material is engaged by the number of punch and die sets A which are required to produce the desired sleeves.

The punch and die set B, which produces the front row 82 of sleeves 20 (FIGURE 9) in the finished three-row fin 19 includes die pairs B1, B2 and B3 (FIGURE 2A) which correspond in' size and spacing lengthwise of the punch and die assembly with the punch and die pairs A1, A2 and A2. The punch and die set B, which is preferably along the same line as a punch and die set A, in this ernbodiment, does not include a punch and die pair corresponding to the punch and die pair A4. It was found that there was adequate space provided between a B2 dimple and a C1 dimple (FIGURE 5B) in this particular arrangement to eliminate the smallest punch and die pair 21 in sets B and C. However, as shown in FIGURE 3F, the punch and die pair A4 is required in the rear row 81 to provide space for large dimples in the adjacent, front row 82 of the following fin. The operation of the punch and die pair A., is performed in the B set by the punch and die pair A22.

The next punch and die pair B22 in the punch and die set B, which engages the sheet material after the punch and die pair B2, performs its operation after six advancements of the sheet material following the operation performed therein by the punch and die pair B2. As in the case of the punch and die set A, operations are performed upon the dimple 25 by the punch and die pairs B22 and B22 in the third and fifth advancements after punch and die pair B22 has performed, in substantially the same manner as discussed above with respect to the functions performed by the punch and die pairs A22 and A22, to produce sleeves 20B.

In the meantime, the punch and die pairs C1, C2 and C3, as well as the punch and die pairs C22, C23 and C2.,l will perform their dimpling, punching and drawing operations in sequence to form the sleeves 20C, just as the punch and die set B formed the sleeves 20B. As in the case of the punch and die set B, the punch and die set C includes punch and die pairs C1, C2 and C2 only, the function of A4 in the punch and die set A being performed by the punch and die pair C22. The punch and die pairs in the punch and die sets A and B are arranged so that the punch and die pairs in the punch and die sets C can perform their operations in uniformly spaced steps.

The line of punch and die pairs in the punch and die set C (FIGURES lA and 1B) is offset from the line containing the punch and die pairs of the punch and die sets A and B, which results in the diamond-shaped configuration of the finished sleeves 20A, 20B and 20C (FIG- URE 9).

As in the case of the punch and die set A, the punch and die sets B and C are duplicated crosswise of the punch and die construction 10 so that they produce rows of identical dimples and sleeves crosswise of the sheet material.

In the foregoing descriptive material with respect to the punch and die sets, reference has been made to the fact that each sleeve has an operation performed thereon during its progression through the punch and die assembly at a minimum of every other or every second advancement of the sheet stock. Thus, it will be seen that the arrangement of punch and die pairs in the three sets A, B and C is such that no punching operation is performed upon the portion of the sheet material resulting in a given three-row fin 19 at every other operation of the press where the advancement is, as set forth above, equal to the centerline distance between corresponding rows in two adjacent fins. However, it has been found that a -better fin structure is produced by alternating the forming operations between adjacent fins as the sheet stock is moved through the punch and die assembly so that a short delay occurs between each operation performed upon any given portion of the sheet material.

A six-row fin 83 (FIGURE 22) having a diamond pattern can be produced with the assemblies 11 and 12 by changing the stroke of the shear 18 so that it separates each fin from the remainder of the sheet material after every second advancement thereof.

The feed mechanism 17 (FIGURE 2B) for advancing the sheet material, as discussed above, is comprised of a support plate 86 (FIGURES 2A and 2B) which is located near the front end of the machine and which has a plural pair of adjacent, elongated slots and 87, which are coaxial with the lengthwise extent of the lines of punch and die sets A and C, respectively. The length of each slot 85 and 87 is substantially longer than the centerline distance between corresponding rows in two adjacent fins. That is, said slots are substantially longer than the distance which the sheet material is moved during each advancement. An opening 88 is provided in alignment with and forwardly of each slot 87 at a distance from said slot slightly less than twice the length of an advancement of said sheet material minus the diameter of a sleeve 20.

A shuttle 89 (FIGURE 1B) is supported upon a pair of slide rods 92 and 93 (FIGURE 2B) located on opposite sides of the punch assembly 11 so that said shuttle can reciprocate frontwardly and rearwardly. Springbiased pins 94 and 95 are supported upon the shuttle 89 for extension upwardly through said slots 87 and 85, respectively, to be received within the openings 96A and 96C (FIGURE 7B) in the sleeves 20A and 20C, for example. The pins 94 and 95 are sloped downwardly and rearwardly so that they will advance the sheet forwardly, but will slide out of the openings 96A and 96C when the shuttle is moved rearwardly. A holding pin 97, which also has a rearwardly and downwardly sloping upper surface, is receivable into the openings 96C for holding the sheet material against rearward movement as the shuttle 89 is moved rearwardly to take its position for effecting another forward advancement of the sheet material.

The shear 18 may be of a substantially conventional type wherein a blade 98 is mounted upon a blade support 99 adjacent the front end of the support plate 86 for vertical, reciprocable movement so that the blade makes shearing contact with the shearing edge of a bar 102 at the forward end of the punch assembly 11.

OPERATION It will be seen from the foregoing descriptive materials that the sheet material 16 is fed into the punch and die construction 10 from the rearward end thereof. After the sheet stock has Abeen fed through the machine to the point where it can be engaged by the pins on the shuttle 89, the feeding of the sheet material can then be entirely automatic. By referring to FIGURES 3A through 3F, inclusive, FIGURES 5A through 5D, inclusive, and FIGURES 7A and 7B, the progression of changes in any given portion of the sheet material can be seen. That is, the dimples appearing in FIGURE 3A, which are produced by the punch and die pair A1 are in the rear row of a particular three-row fin 19 and these dimples ultimately become the fiared sleeves 20 in the portion 19A of FIGURE 7B, after that portion of the sheet material has advanced from the rearward end to the frontward end of the punch and die assemblies, where the shearing operation is performed. FIGURES 4A through 4F, 6A through 6D, 8A and 8B illustrate -by sectional views the contours of the deformations provided by the various punch and die pairs during the sequence of operations performed upon the sheet material as it moves from the rearward to the frontward end ofthe punch and die assemblies,

If it becomes desirable to convert the punch and die assembly 10 from an operation producing three-row fins or any whole number multiple thereof, into a punch and die assembly capable of producing two-row fins or any whole number multiple thereof, such can be quickly and easily effected merely by removing the shim bars 48, 48A and 48B. The shim bar 48B is replaced by a narrower shim bar which will support the punches 29C1 without supporting the punches 29B3. Thus, the punch and die pairs B1, B2 and B3 are deactivated, as indicated by FIGURES 15A and B.

The feed mechanism 17 (FIGURES 1B and 2B) is adjusted so that the stroke of the shuttle 89 is equal to the centerline distance -between the front and rear rows 82 and 81, respectively, in a three-row fin 19. That is, the feed strokes of the pins 94 and 95 are reduced to twothirds of their length for a three-row fin.

If the punch and die construction 110 (FIGURES 15A and 15B) is operated after these minor adjustments, the punch and die sets A and C will produce two-row fins 112 (FIGURE 18) having sleeves 111 arranged in a staggered pattern.

FIGURES 16A, 16B and 16C disclose adjoining portions of a strip of sheet material 16A upon which a proof of the punch and die construction 110 has been made. That is, the numbered and lettered circles are located where impressions will be made in the sheet material by the construction 110 each time the press is operated after said construction is adjusted for two-row fins 112. The small lines 113 (FIGURE 16A) indicate the amount of ad- 'vancement of the sheet material 16A during each stroke of the feed mechanism.

In this embodiment, any selected part of the sheet 16A is advanced 46 times from its point of entry at the rear end of the construction 110 to its point of discharge, where it is sheared, at the front end of the construction. The numbers between the lines 113 (FIGURES 16A and 17A) indicate such advancement, each of which is equal to twice the centerline distance lbetween the two rows of sleeves in the finished fin 112. Thus, where the punch and die assemblies of the construction 10 are used (after conversion) to make two-row fins, there are at least three advancements of each part of said sheet material, upon which operations are performed by the punch and die assemblies, between each such operation.

However, operations are performed upon the sheet material 16A following each advancement thereof. Thus, the adjoining portions of the sheet material 16B shown in FIGURES 17A, 17B and 17C illustrate a strip of sheet material as it appears in the punch and die construction during normal operation.

By referring to the crossed centerlines 116y in FIGURES 15A and 16A, it will be seen that the above-described advancements are required to provide a staggered pattern from a punch and die construction designed to produce a three-row diamond pattern.

The punch and die construction 110 can be arranged to produce four-row fins 117 (FIGURE 20) by adjusting the shear 18 (FIGURE 2B) so that it cuts the material 16B (FIGURE 17C) only after two advancements of said material. Similar adjustments can also be made to produce six-row ns 118 (FIGURE 2l) or other whole number multiples of the two-row lin.

The numbers in the circles of FIGURES 16A and l'7A, for example, correspond to the punch and die pairs of FIGURE 1A. The letters D, P and F in the circles of FIGUR-ES 16B, 16C, 17B and 17C correspond, respectively, to the functions of drawing, punching and flanging which are performed by the punch and die pairs in these locations.

Although particular preferred embodiments of the invention have been disclosed above for illustrative purposes, it will be recognized that variations or modifications of such disclosure, which come within the scope of the appended claims, are fully contemplated.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A punch and die construction for producing progressively a plurality of uniformly arranged distortions in a strip of sheet material while intermittently advancing said sheet material through said construction unidirectionally in uniform increments, the combination comprising:

a first set of punches and cooperating dies arranged in pairs at spaced intervals along a line parallel with said direction, the length of each interval being a multiple of the length of the increment of advancement;

a second set of punches and cooperating dies arranged in pairs at spaced intervals along a line parallel with said direction, the length of each interval being equal to a multiple of the length of the increment of advancement, and the line of said second set being offset laterally from the line of said first set, some of the intervals in at least one of the sets being longer than the other intervals in said one set.

2. A construction according to claim 1, wherein the distance between adjacent pairs in each set is not less than whole number multiples of the increment of advancement; and

including shear means located adjacent the end of said construction in said direction and arranged for shearing said sheet material transversely of said direction after selected advancements of said material.

3. A punch and die construction for producing progressively a plurality of uniformly arranged and integral sleeves in a strip of sheet material while intermittently advancing said sheet material through said construction unidirectionally in uniform increments, the combination comprising:

a first set of punches and cooperating dies arranged in pairs of plural sizes at spaced intervals along a first line parallel with said direction, the length of each interval being a multiple of the length of the increment of advancement;

a second set of punches and cooperating dies arranged in pairs of plural sizes at spaced intervals along a second line parallel with and spaced from said first line, the length of each interval being equal to a multiple of the length of the increment of advancement;

a third set -of punches and cooperating dies arranged in pairs of plural sizes at spaced intervals along said rst line, the length of each interval being a multiple of the length of the increment of advancement, some of said pairs in said third set being located between pairs in said first set, and some of the intervals in at least one of said sets being longer than the other intervals in said one set.

4. A construction according to claim 3, including a plurality of rst, second and third sets of punch and die pairs, said sets being arranged in alternating first and second, substantially uniformly spaced and parallel lines, said first and third sets being in said lirst lines and said second sets -being in said second lines, the punch and die pairs of each first, second and third set being respectively aligned transversely of said direction with the punch and die pairs of the other first, second and third sets.

5. A construction according to claim 4, wherein the sizes of the punch and die pairs in said sets are reduced in said direction; and

wherein the size of the largest punch and die Apair in each set is not less than the centerline distance between the closest adjacent sleeves formed in said sheet material.

6. A construction according to claim 4, including means for dcactivating said third sets of punches and dies, whereby said punch and die construction is converted from from a diamond-shaped pattern to a zigzag pattern, in said direction.

7. A construction according to claim 4, wherein the intervals between adjacent pairs in each set are not less than twice said increment of advancement; and

including shear means located at the end of said construction in said direction and arranged for cutting said strip transversely of said direction, each cut being made after a uniform number of said advancements.

8. A construction according to claim 4, wherein the size of the diameter of the largest punch in each set is greater than the centerline distance between the closest adjacent sleeves formed in said sheet material;

wherein the interval between two adjacent pairs in said sets is not less than twice the increment of advancement; and

wherein the distance between the first and last pairs in said second set is less than the distance between the first and last pairs in said first and third sets.

9. A construction according to claim 8, wherein four pairs in each of said first sets engage each portion of said sheet material as it is moved in said direction before said material is engaged by the pairs in said second and third sets, and two pairs in each of said third sets engage said sheet material as it is moved in said direction before said material is engaged by the pairs in said second set.

10. A method for forming in a sheet of malleable material a plurality of integral and closely spaced sleeves in a uniform pattern, the steps comprising:

advancing said sheet material intermittently and unidircctionally in uniform amounts along a path;

arranging plural pairs of cooperating punches and dies in plural, spaced lines parallel with and adjacent to said path, there being two different arrangements of said pairs disposed in alternating, first and second lines;

causing at least three pairs of punches and dies in each of said first lines to perform operations upon a portion of said sheet material;

thereafter causing pairs of punches and dies in each of said rst and second lines to perform operations upon said portion; and

shearing said sheet material transversely of said path after a selected number of said advancements.

References Cited UNITED STATES PATENTS 1,000,144 8/19'11 Beebe 113--1 1,005,622 10/ 1911 Eisenbeis 72-405 2,260,891 10/ 1941 Ekstedt et al. 72-333 2,867,723 3/ 1959 Lawrence 113-1 3,182,483 5/ 1965 Karmazin 72--405 CHARLES W. LANHAN, Primary Examiner.

E. M. COMBS, Assistant Examiner. 

1. A PUNCH AND DIE CONSTRUCTION FOR PRODUCING PROGRESSIVELY A PLURALITY OF UNIFORMLY ARRANGED DISTORTIONS IN A STRIP OF SHEET MATERIAL WHILE INTERMITTENTLY ADVANCING SAID SHEET MATERIAL THROUGH SAID CONSTRUCTION UNIDIRECTIONALLY IN UNFORM INCREMENTS, THE COMBINATION COMPRISING: A FIRST SET OF PUNCHES AND COOPERTING DIES ARRANGED IN PAIRS AT SPACED INTERVALS ALONG A LINE PARALLEL WITH SAID DIRECTION, THE LENGTH OF EACH INTERVAL BEING A MULTIPLE OF THE LENGTH OF THE INCREMENT OF ADVANCEMENT; A SECOND SET OF PUNCHES AND COOPERATING DIES ARRANGED IN PAIRS AT SPACED INTERVALS ALONG A LINE PARALLEL WITH SAID DIRECTION, THE LENGTH OF EACH INTERVAL BEING EQUAL TO A MULTIPLE OF THE LENGTH OF TJE INCREMENT OF ADVANCEMENT, AND THE LINE OF SAID SECOND SET BEING OFFSET LATERALLY FROM THE LINE OF SAID FIRST SET, SOME OF THE INTERVALS IN AT LEAST ONE OF THE SETS BEING LONGER THAN THE OTHER INTERVALS IN SAID ONE SET. 